A video-based surgical target system is known from U.S. Pat. No. 5,765,561, for which among other things the use of a tracked video camera is proposed, whose images are superimposed onto assigned images from radioscopic imaging methods and/or tomographic imaging methods on the statically arranged screen of a navigation system. A particular disadvantage of such an embodiment is that the physician wishing to view the images always has to look away from the patient, to the screen of the navigation system. He can then no longer pay exact attention to the position in which the camera is, i.e. the exterior position from which he is obtaining the superimposed images. The system is therefore somewhat awkward and does not enable direct inspection within the part of the patient's body.